Conventionally, on English word processors and personal computers handling documents written in Western languages, when a document is displayed on a screen or printed on paper, word-wrapping is performed whereby, to prevent a word from being cut halfway and arranged on adjoining lines, a new line is started immediately before that word. For example, Japanese Patent Application Laid-Open No. H2-27468 proposes a document creating device wherein character data that represents the characters and symbols entered via a keyboard is temporarily stored in a buffer, and the thus stored character data is sequentially read out from the buffer in such a way that, while word-wrapping is performed on those parts of the character data that happen to be located beyond the previously set display area, the character data is displayed on the screen in a display section.
However, simply performing word-wrapping results in varying blank lengths at the right-hand ends of different lines, making the document appear untidy. To avoid this, justification is often performed in combination whereby extra spaces are inserted between adjoining words to make the left-hand and right hand ends of different lines flush.
The problem here is that, when word-wrapping is performed on a word consisting of a large number of characters and justification is performed on the line preceding that word, this line looks too widely spaced, making the document appear not much better than without such manipulation. To avoid this, hyphenation is further performed in combination whereby a word is divided at a division point between adjoining syllables and arranged on adjoining lines with a hyphen inserted in between.
However, whether to perform hyphenation or not needs to be decided by the operator who is entering the document after tentatively displaying and evaluating the appearance of the document as expected to be obtained when a given word is arranged on adjoining lines. This imposes a heavy burden on the operator.
There have conventionally been proposed also techniques for lessening the burden on the operator before hyphenation. For example, Japanese Patent Application Laid-Open No. H1-116758 proposes a document processing device provided with a line selecting means, a character string moving means, and a division point changing means wherein a document is displayed in a format having hyphens inserted appropriately or in a format close thereto in order to less rely on the operator's operation when deciding whether or not and where to divide given words.
Word-wrapping and hyphenation are, in general, useful to display a document in a readable format. However, quite inconveniently, when applied in cellular phones, portable terminal devices, and the like, i.e., in appliances provided with a display section that can display only a small number of characters per line on the screen thereof, word-wrapping reduces the amount of information that can be presented at a time and hyphenation rather makes a document more difficult to read. This is because, where only a small number of characters can be displayed per line, word-wrapping and hyphenation are performed excessively frequently.
Specifically, frequently performing word-wrapping results in lowering the efficiency with which the display area is used, i.e., the proportion of the area in which characters are actually displayed relative to the whole available display area. This reduces the amount of information that can be presented at a time. Frequently performing hyphenation does not lower the efficiency with which the display area is used, but causes too many words to be divided between adjoining lines. This makes a document difficult to read. Justification helps improve the appearance of a document by leveling out the differences among different lines in the number of characters displayed thereon resulting from word-wrapping, but does not contribute to the improvement of the efficiency with which the display area is used.